Sialic carbohydrates

ABSTRACT

The invention relates to the use of sialic carbohydrates of general formula (I), containing at least one carbohydrate unit of general formula (II) for the immune modulation, immune suppression and in the prevention and treatment of infections in humans and animals. In said formula (II), Sia represents a sialic acid or a sialic acid derivative in an α2-3 bond, Gal represents a galactose-monosaccharide-unit, HexNac represents an N-acetylated galactosamine or glucosamine-monosaccharide-unit (GalNAc or GlcNAc), Hex represents a galactose- or glucose-monosaccharide-unit (Gal or Glc), C represents HexNac or Hex or is absent, n represents 1-50, V represents OH, a carbohydrate radical or a connecting point on a support T, with the proviso that if V represents OH, n represents 1, and if V represents a carbohydrate radical or a support T, n represents the number of carbohydrate unites of general formula (II) directly connected to said carbohydrate radical or support, X represents a sialic acid or a sialic acid derivative, wherein a second sialic acid or a sialic acid derivative or more sialic acid or sialic acid derivatives can be connected to an α2-8 bond, a phosphate, a sulphate, or carboxyl-group or a monosaccharide having a phosphate, sulphate, or carboxyl group and only one of the radicals X is present.

The invention relates to the use of carbohydrates for immunomodulation,immunosuppression and for treating infections in humans and animals, andto food, dietetic and pharmaceutical compositions containing thesecarbohydrates.

The adhesion of pathogenic organisms, as well as of cell-damagingsubstances to the surface of mammal cells is the first step and anessential prerequisite for an infection or a damage of the cell. Theinteraction between the pathogens and the cells is formed by aligand-receptor relationship. In this ligand-receptor relationships orinteractions, glycosidic structures play an important role.

One possibility of influencing such ligand-receptor relationshipsconsists in blocking the respective receptors or ligands, respectively,of one of the two cell surfaces or of both cell surfaces.

Using specific test systems, it could be shown that various carbohydratemixtures reduce or even completely prevent the adhesion of, for example,micro-organisms to the cell surface, cf.: Kunz, C; Rudloff, S. ActaPaediatr. 1993, 82, 903-912. Other substances such as the Lewisstructures as the carbohydrate ligands of selectines (adhesion proteinson endothelial cells and lymphocytes) modulate the interaction oflymphocytes with the endothelium, for example, within the scope ofrolling, homing and the invasion during inflammatory processes (AlbeldaS. M., Smith C. W., Ward P. A., FASEB J. 1994, 8, 504-512). The group ofsialic acids yields an important contribution in the above-mentionedpathogen-cell interactions on the one hand and in cell-cell interactionson the other hand. These monosaccharides deploy their action inparticular as components of oligosaccharides and glycoconjugates such asglycolipids and glycoproteins (Traving and Schauer, Structure, functionand metabolism of sialic acids, Cell. Mol. Life Sci., Vol. 54, 1998).Sialic acids are to be found in up to 40 different derivatization forms,and have hitherto been detected in humans, animals and some viruses,bacteria and fungi.

Apart from the chemico-physical effect of the negative charge of thecarboxyl group, the main function of sialic acids is their specificparticipation in molecular and cellular recognition processes (Kelm S. &Schauer R. (1997), Sialic acids in molecular and cellular interactions,Int. Rev. Cytol. 175, 137-240). A part thereof is the stabilization ofenzymes and other proteins, autorecognition/non-autorecognition of theimmune system, masking of cells and proteins. Siglecs (P. R. Crocker etal. (1998) Siglecs—a family of sialic acid-binding lectins, Glycobiol.,8, Glycoforum 2 v-vi.) constitute a particular class of sialicacid-specific lectins. These molecules have immunoglobulin-like domains,represent lectin-like receptors, and, as an essential feature, bindsialic acid.

In cell-cell interactions, the structure of the ligands or receptors isgenerally essential for the action mechanism of these interactions. Thebinding process of a ligand to a receptor is the first event that maylead to a triggering of further signal cascades, Also in the case ofsiglecs, it could be shown that these participate in signal transductionmechanisms. Thus, tyrosines, which are for example present in theSiglec-2 (CD22) may undergo a phosphorylation, which in turn, andthrough further intermediate steps, leads to a reduced activation ofB-cells.

The binding mechanism of specific proteins to carbohydrate structures isalso of importance for the adhesion of bacteria to epithelial surfaces.Since the adhesion represents the first step of a first infection, theinhibition of this binding process is an important objective in avoidinginfections.

The bacterial lectins (adhesins) specifically recognizing α2-3 aresubject to the same mechanism that applies also to the siglecs.

Moreover, what is known as clustering both of receptors and ligandsplays an important role in the binding intensity. An important criterionis in this case the polyvalence of the binding-active ligands. The moreligand structures are combined in a molecule, the more pronounced theinteractions between ligands and receptors or between two or more cellsmay be. This applies in particular for interactions where across-linkage of molecules or cells modulates the function of abiological process. It thus has to be emphasized that polyvalent ligandslead to a cross-linkage of receptors and hence may provoke anothersignal effect.

The object of the present invention is to show a way how animmunomodulation, immunosuppression and a treatment of infections inhumans and animals may be achieved with the help of carbohydrates.

This object is solved by the teachings of the claims.

According to the invention, the sialyzed carbohydrates of the followinggeneral formula I having at least one carbohydrate unit of the followinggeneral formula II

wherein

-   -   Sia means a sialic acid or a sialic acid derivative in an α2-3        bond,    -   Gal means a galactose-monosaccharide unit,    -   HexNac means an N-acetylated galactosamine-monosaccharide unit        or glucosamine-monosaccharide unit (GalNAc or GlcNAc),    -   Hex means a galactose-monosaccharide unit or        glucose-monosaccharide unit (Gal or Glc),    -   C represents HexNac or Hex or is absent,    -   n represents 1 to 50,    -   V represents OH, a carbohydrate residue or a connecting point on        a carrier T, with the proviso that if V represents OH, n        represents 1, and, if V represents a carbohydrate residue or a        carrier T, n means the number of the carbohydrate units that are        each directly bound to this carbohydrate residue or carrier and        which are of the general formula II    -   X means a sialic acid or a sialic acid derivative thereof,        wherein a second sialic acid or a sialic acid derivative or        several sialic acids or sialic acid derivatives can be bound to        the sialic acid or the sialic acid derivative in an α2-8 bond, a        phosphate group, sulphate group or carboxyl group, or a        monosaccharide including a phosphate group, sulphate group or        carboxyl group, and only one of the residues X is present,    -   are used for the immunomodulation, immunosuppression and        prevention as well as treatment of infections in humans and        animals.

Surprisingly, it has been found that rather than the initially mentionedoligosaccharide sequences, the inventively used carbohydrates are highlyefficient inhibitors or receptor analogues. These carbohydrates willhereinafter be called “inventive carbohydrates”.

The inventive carbohydrates must feature at least one carbohydrate unitof the general formula II [Siaα2-3-Gal-HexNac(X)-Hex(X)—C-]-; in thiscase, the residues Sia, Gal HexNac, Hex, X and C have the meaningsindicated in conjunction with general formula I.

This carbohydrate unit of the general formula II thus constitutes acomponent of the inventive carbohydrates of general formula I. If theresidue V in the formula of general formula I represents OH, then thecarbohydrates of general formula I are made up of a carbohydrate unit ofthe general formula II and this residue V.

In the sialyzed carbohydrates, the preferred linkages are the following:α1-2, α1-3, α1-4, α1-6, α2-3, α2-6, α2-8, β1-2, β1-3, β1-4, and β1-6. Ina carbohydrate or glycan, one as well as several of the mentioned bondsmay occur. Preferred are β-linked base structures (I, II) with chargeda-glycosidic groups, insofar as X also stands for a glycan.

The residue V may also represent a carbohydrate residue or a linkagepoint on a carrier T. In the latter case, V, strictly speaking, does notmean a residue but just this linkage point. Via this linkage point, thecarbohydrate unit of the general formula II is bound to a carrier or isimmobilized thereon. The kind of carrier is not particularly critical sothat any one of a large number of carriers may be used. Up to 50carbohydrate units of general formula II may be bound to such a carrier,each of which carbohydrate units is bound or coupled to this carrier Tthrough the linkage point V. The index n used within the framework ofthe present documents thus stands for the number of carbohydrate unitsof the general formula II, and not, for instance, a chain of n-elementsof this carbohydrate units.

Where it is stated that n represents 1-50, then this means that nrepresents an integer from 1 to 50, and hence may represent 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,42, 43, 44, 45, 46, 47, 48, 49 and 50.

The carrier T is in particular a peptide, a protein, a polymer or abiopolymer, with the linkage with the peptide or protein in particularbeing N-glycosidic or O-glycosidic. Polyhydroxybutanoic acid may be usedas biopolymer. A suitable polymer is, for example, polyacrylamide.

The residue V may also represent a carbohydrate residue. This ispreferably a monosaccharide residue, oligosaccharide residue orpolysaccharide residue. Examples may be the following: milkoligosaccharides, reserve carbohydrates (in particular starch) andskeletal carbohydrates such as pectins, celluloses and galactomannans.While it is true that these carbohydrates may also be calledbiopolymers, for a better terminological delimitation they will not besubsumed under the above-mentioned biopolymers for the purposes of thepresent invention.

The carbohydrate residue representing the residue V may also be one ormore (even aliphatic) carbohydrate residue(s) composed like thecarbohydrate units of general formula II, with the bonds of thesecarbohydrate residues being different.

It is crucial that the carbohydrate unit of general formula II has atleast two negative charges present on a nucleus of at least 3 and inparticular 4 neutral monosaccharides (Gal, HexNac, Hex and C). One ofthese negative charges is located on the non-reducing end of the nucleus(it may also be designated as core) as an α2-3 linked sialic acid on agalactose. The second charge is also present in a subterminal locationas a sialic acid, which, however, may be substituted by other chargedgroups, i.e. phosphate, sulphate or carboxyl groups. These phosphate,sulphate and carboxyl groups may be located directly at themonosaccharides HexNac and Hex or may be bound to anothermonosaccharide. In other words, this other monosaccharide will thenrepresent the bridge between this charged group and the monosaccharideHexNac or Hex of the carbohydrate unit of general formula II.

If the residue V is a carbohydrate residue corresponding to thecarbohydrate unit of general formula II as far as its composition isconcerned, then preferably those residues V are used in which twonegative charges per 3 or 4 neutral monosaccharides are present.

In the carbohydrate units of general formula II, only one of theresidues X is present. In other words, it is either the monosaccharideHexNac or the monosaccharide Hex that carries a residue X of the abovementioned kind.

If monosaccharides are mentioned within the framework of the presentdocuments for explaining the general formulae I and II, then, strictlyspeaking, the term “monosaccharide unit” would have to be used, sincethese monosaccharides are not present in an isolated form but are boundto other monosaccharides or groups. For the sake of simplicity, however,only the term monosaccharide or the specific name of the monosaccharide(e.g. galactose, glucose, hexosamine, etc.) will be used.

The monosaccharide unit designated Sia preferably is acetyl neuraminicacid (NeuAc) or N-glycolyl neuraminic acid (NeuGc). The O-acylderivative of the sialic acid of the residues Sia and X, for example, isan O-acetyl derivative.

If the residue X signifies a sialic acid or an O-acyl derivative, thenit is preferably NeuAc, NeuGc and the derivatives thereof, e.g.O-acetylated sialic acid in an α2-3 bond or an a2-6 bond.

As already explained above, a second sialic acid or several sialic acidsmay be present on the residue X in an α2-8 bond.

While the α2-3 bound Neu5Ac (residue Siaα2-3 in the general formulae Iand II), in order to produce a bond, absolutely must be present in thecarbohydrates used according to the invention as a necessary recognitionsequence, the second and third Neu5Ac are only necessary because of thecharge in order to increase the affinity. The kind of bond is then notimportant. This second Neu5Ac (residue X) may also be substituted byanother group carrying a negative charge (phosphate, sulphate, carboxyl,also in the form of carboxylate).

For the immunomodulation, immunosuppression and the treatment ofinfections in humans and animals with the help of the inventivecarbohydrates, primarily the carbohydrate units of general formula IIare thus of importance. The kind of the carrier T to which thesecarbohydrate units of general formula II may be bound, is therefore of asubordinate importance. The carrier T may therefore be of any desiredkind. Preferably, it is a carbohydrate, a peptide, a protein, a polymeror a biopolymer, with the linkage with the peptide or protein preferablybeing N-glycosidic or O-glycosidic. More preferably, the carrier Tconsists of lipophilic compounds including one or more carbohydrateunit(s) of general formula II which represent(s) the head group(s)thereof. Preferred lipophilic compounds are glycolipids andgangliosides.

As the carbohydrate of general formula I, disialyl-lacto-N-tetraose(DS-LNT), disialyl-lacto-N-neo-tetraose (DS-LNnT), glycomacropeptide(GMP) and the gangliosides G_(D1a), G_(T1b) and G_(T1c) are used. TheGMP preferably originates from animal milks such as sheep, goat,buffalo, camel and in particular cow milk.

The carbohydrates used according to the invention, be they freecarbohydrates (V stands for H₂O) or carbohydrates bound to acarbohydrate residue or to a carrier T, may or will be incorporated intovarious food, dietetic and pharmaceutical compositions. All of thesecompositions may be present in a fluid or solid form. The term “foodcomposition” used herein not only comprises the actual food compositionbut also food additives, food supplements, beverages and foodcompositions including infant and baby formulae. The term “baby orinfant formulae” refers in particular to all artificially preparedformulae, in particular for human babies but no human milk. “Artificial”means those infant formulae which are produced from vegetable or animalraw materials but not from human origin. These food compositions may beadministered to a human being or an animal in any desired way. This alsoincludes administration into the stomach as a probe food.

The carbohydrates according to the invention may, for example, be addedas admixtures or additives to the following products, although thisenumeration is not conclusive: milk and milk products, infant andbabyfood formulations, chocolate bars, yoghurt drinks, cheese, sausageand meat products, anabolic food, probe food and products for pregnantwomen.

The carbohydrates according to the invention may also be administered inthe form of a pharmaceutical composition alone or together with one orseveral additional active agent(s). These compositions may, for example,be formulated as a tablet/sachet. For the formulation of suchpharmaceuticals, usual adjuvants, carriers, auxiliary agents, diluents,moisturizing agents, thickening agents, flavoring agents, sweeteningagents, etc. may be used.

The pharmaceutical compositions may be administered in any usual way toa patient (i.e. human and animal). However, for the sake of convenience,they will be compositions suited for oral, lingual, nasal, intestinal,bronchial, vaginal, topical (skin and mucosa) and per os administrationand formulated to suit the kind of administration.

The foods, dietetic compositions and pharmaceutical compositionscontaining at least one carbohydrate used according to the invention,may be used among other things for preventing and treating infections ofthe gastrointestinal tract, e.g. in case of listerioses, of the bloodsystem, the respiratory passages, the urogenital tract, as well as ofthe nasopharynx, and for protecting endothelia, epithelia and mucosa.Thus, they may be applied topically to the skin or may also be used onmucous membranes. These mucous membranes include nasal, intestinal,bronchial and vaginal mucous membranes. Thus, the carbohydrates usedaccording to the invention may, for example, be added to a mouthwash.All age groups, ranging from new born babies up to elderly people, maybe mentioned as target groups for the carbohydrates used according tothe invention. Special fields of application are the protection and thetreatment of pregnant women, sick persons, debilitated and elderlypeople, for whom the prevention e.g. of a listeriosis is of particularimportance.

Due to their anti-adhesive properties, the inventive carbohydrates canthus be used for reducing or preventing an infection. On the other hand,they can also serve the purpose of influencing the immunologicalresponse by modulating cell-cell interactions. This applies both to themodulation of cell-cell interactions preferably between eucaryonticcells (e.g. lymphocytes and endothelial cells, etc.) and for themodulation of the adhesion of pathogens (such as bacteria, spores,viruses, viroids, prions, fungi, monocellular and multicellularparasites, toxins and heavy metal cations) on eucaryontic cells,preferably mammalian cells.

The carbohydrates used according to the invention are known compounds,e.g. DS-LNT, DS-LNnT and the gangliosides G_(D1a), G_(T1b) and G_(T1c).They are known and/or may be prepared according to suitable knownmethods in a chemical or enzymatic way, or in a combination of these twotechnologies.

The disialyl-lacto-N-tetraose (DS-LNT) and disialyl-lacto-N-neo-tetraose(DS-LNnT) used according to the invention are compounds of generalformula I, in which HexNac=GlcNac, Hex=galactose and C=glucose. Inaddition, two sialic acids are present (Siaα2-3NeuAc, X=α2-6NeuAc). Alsothe derivatives thereof may be used, which are preferably those wherethe non-terminal sialic acid has been substituted by a glycolylneuraminic acid, a sulphate group, a phosphate group or a carboxyl groupor carboxylat group. A further sialic acid may also belinked. The type 1lactosamin unit may be replaced by a Gal (β1-3) GalNAc unit.

In the gangliosides G_(D1a), and G_(T1b) which are further usedaccording to the invention, the monosaccharide sequence is very similarto DS-LNT. The bonding of the second or third sialic acid, however,takes place on the galactose localized on the glucose (junction to theceramide).

The carbohydrates of general formula I used according to the inventionappropriately are administered in such an amount, that a patientpreferably is supplied once daily with at least 1 mg of carbohydrate ofgeneral formula I, and in particular one carbohydrate unit of generalformula II per kg of body weight.

Exemplary dietetics and pharmaceuticals are listed below which containat least one inventive carbohydrate. These are the following inventivecarbohydrates: disialyl-lacto-N-tetraose (DS-LNT) and the derivativesthereof (see above), DS-LNnT and the derivatives thereof, and G_(D1a),G_(T1b) and G_(T1c). For the sake of simplicity, these carbohydrateswill simply be termed “inventive carbohydrate” in the examples. Thisterm is representative for each of the above-mentioned inventivecarbohydrates and the mixtures thereof.

EXAMPLE 1

For preparing sachets, in each case 100 mg or only 5 mg of an inventivecarbohydrate are mixed in a dry state with 990 mg of maltodextrin, andthen are packed in sachets. These sachets are administered three timesper day during meals.

EXAMPLE 2

A known medicinal food (i.e. Milupa® HN 25, balanced diet) in the formof a bead product containing 18.8 g of protein, 8.6 g of fat, 62.8 g ofcarbohydrates, 3.3 g of minerals and vitamins, is admixed in acomposition known per se with an inventive carbohydrate in such anamount that 50 mg of the inventive carbohydrate are contained in 100 gof the finished bead product.

For the composition of a liquid medicinal food, 100 ml of the knownmedicinal food Milupa HN 25 liquid (2.3 g of protein, 1.6 g of fat, 8.5g of carbohydrates, 37 g of minerals and vitamins) are admixed with 7 mgof an inventive carbohydrate.

EXAMPLE 3

A product for Pregnant Women

An effervescent tablet (final weight 4.15 g) (Neovin® from Milupa) isprepared in a manner known per se by admixing 200 to 500 mg of aninventive carbohydrate. One tablet per day is dissolved in 150 ml waterand swallowed.

EXAMPLE 4

A Product for the Elderly and Debilitated Persons

A balanced pulverized medicinal food (Dilsana® from Milupa) containing22.5 g of protein, 7.7 g of fat, 60.8 g of carbohydrates, 5.4 g ofminerals and vitamins is prepared in a manner known per se byincorporating 100 mg to 1000 mg of an inventive carbohydrate per 100 gof powder. Up to 3×50 g per day of the food are dissolved in 150 mlwater and administered.

EXAMPLE 5

Tea

100 g of an instant tea powder prepared in the usual manner are mixedwith 2 g of an inventive carbohydrate. 3.8 g of tea powder are dissolvedin 100 ml of hot water, and administered three times per day.

EXAMPLE 6

A protein-adapted infant milk formulation (Aptamil® from Milupa)containing 11.8 g of protein, 56.9 g of carbohydrates, 24.9 g of fat,2.5 g of minerals and vitamins and 45 mg of taurine are prepared in theusual manner in the form of a bead product, which is mixed with 100 mgto 1000 mg of an inventive carbohydrate per 100 g of infant milkformulation.

1. Use of sialyzed carbohydrates of the following general formula Ihaving at least one carbohydrate unit of the following general formulaII:

wherein Sia means a sialic acid or a sialic acid derivative in an α2-3bond, Gal means a galactose-monosaccharide unit, HexNac means anN-acetylated galactosamine-monosaccharide unit orglucosamine-monosaccharide unit (GalNAc or GlcNAc), Hex means agalactose-monosaccharide unit or glucose-monosaccharide unit (Gal orGlc), C represents HexNac or Hex or is absent, n represents 1 to 50, Vrepresents OH, a carbohydrate residue or a connecting point on a carrierT, with the proviso that, if V represents OH, n represents 1, and, if Vrepresents a carbohydrate residue or a carrier T, n means the number ofthe carbohydrate units that are each directly bound to this carbohydrateresidue or carrier and which are of the general formula II

X means a sialic acid or a sialic acid derivative thereof, wherein asecond sialic acid or a sialic acid derivative or several sialic acidsor sialic acid derivatives can be bound to the sialic acid or the sialicacid derivative in an α2-8 bond, a phosphate group, sulphate group orcarboxyl group, or a monosaccharide including a phosphate group,sulphate group or carboxyl group, and only one of the residues X ispresent, for the immunomodulation, immunosuppression and prevention aswell as treatment of infections in humans and animals.
 2. Use accordingto claim 1, characterized in that one, two, three, four, or all of thefollowing criteria i) through iv) are met: i) Sia represents acetylneuraminic acid (NeuAc) or N-glycolyl neuraminic acid (NeuGc), ii) thesialic acid derivative or the sialic acid derivatives of the residuesSia and X is/are an O-acyl derivative and in particular an O-acetylderivative, iii) the carrier T is a peptide, a protein, a polymer or abiopolymer, with the linkage with said peptide or protein in particularbeing N-glycosidic or O-glycosidic, and iv) the carbohydrate residueconstituting the residue V is a monosaccharide residue, anoligosaccharide residue or a polysaccharide residue.
 3. Use according toclaim 1, characterized in that the carbohydrates of general formula Iare selected from disialyl-lacto-N-tetraose (DS-LNT, V=OH,HexNac=GlcNAc, Hex=galactose (Gal), C=glucose, Sia=α2-3 NeuAc, X=α2-6NeuAc on HexNac), disialyl-lacto-N-neo-tetraose (DS-LNnT),glycomacropeptide (GMP), ganglioside G_(D1a), ganglioside G_(T1b) andganglioside G_(T1c).
 4. Use according to claim 1 any one of claims 1,characterized in that T represents lipophilic compounds, and thecarbohydrate unit or carbohydrate units of general formula II representsor represent the head group(s) thereof.
 5. Use according to claim 4,characterized in that said lipophilic compounds are glycolipids and inparticular gangliosides.
 6. Use according to claim 1, characterized inthat the carbohydrate or carbohydrates of general formula I is/are usedin an amount of at least 1 mg per kg of body weight.
 7. Use according toclaim 1, for the prevention and treatment of infections of thegastrointestinal tract, blood system, respiratory passages, urogenitaltract, as well as the nasopharynx.
 8. Use according to claim 1,characterized in that the carbohydrate or carbohydrates of generalformula I are incorporated into a fluid or solid food composition (withthe exception of human milk), dietetic composition or pharmaceuticalcomposition for administration to a human or an animal, or serve for thepreparation of such a composition for the immunomodulation,immunosuppression and treatment of infections in humans and animals. 9.Use according to claim 8, characterized in that the pharmaceuticalcomposition serves for an oral, lingual, nasal, bronchial, vaginal,topical (skin and mucosa) and per os administration, for anadministration by means of a probe into the stomach of a human or ananimal, or for an administration as an infusion.
 10. Food composition,dietetic composition or pharmaceutical composition containing at leastone carbohydrate of general formula I as described in claim
 1. 11.Composition according to claim 10, characterized in that the compositionmay contain a further carbohydrate or several further carbohydrates,which are different from the carbohydrates of claim 1, a further activeagent or several further active agents and/or a further ingredient,which is known and suited for the corresponding composition, or more ofsuch ingredients, wherein in the case of a pharmaceutical composition ausual auxiliary agent or several usual auxiliary agents, includingdiluents, moisturizing agents, thickening agents, flavoring agents,sweetening agents and carriers, may be present, and in the case of afood composition or a dietetic composition, at least one further foodcomponent may be present.
 12. Method of immunomodulation,immunosuppression and treatment of infections in humans and animals,characterized in that at least one carbohydrate of general formula I ora composition according to claim 10 is administered to a human or ananimal, but not in the form of human milk, in particular in such anamount that at least 1 mg of carbohydrate of general formula I isadministered per kg of body weight to the human or the animal oncedaily.
 13. Sialyzed carbohydrates of the following general formula Ihaving at least one carbohydrate unit of the following general formulaII:

wherein Sia means a sialic acid or a sialic acid derivative in an α2-3bond, Gal means a galactose-monosaccharide unit, HexNac means anN-acetylated galactosamine-monosaccharide unit orglucosamine-monosaccharide unit (GalNAc or GlcNAc), Hex means agalactose-monosaccharide unit or glucose-monosaccharide unit (Gal orGlc), C represents HexNac or Hex or is absent, n represents 1 to 50, Vrepresents OH, a carbohydrate residue or a connecting point on a carrierT, with the proviso that, if V represents OH, n represents 1, and, if Vrepresents a carbohydrate residue or a carrier T, n means the number ofthe carbohydrate units that are each directly bound to this carbohydrateresidue or carrier and which are of the general formula II

X means a sialic acid or a sialic acid derivative thereof, wherein asecond sialic acid or a sialic acid derivative or several sialic acidsor sialic acid derivatives can be bound to the sialic acid or the sialicacid derivative in an α2-8 bond, a phosphate group, sulphate group orcarboxyl group, or a monosaccharide including a phosphate group,sulphate group or carboxyl group, and only one of the residues X ispresent, for the immunomodulation, immunosuppression and prevention aswell as treatment of infections in humans and animals.